1. Field of the Invention
This invention relates to electromagnetic actuators and has particular reference actuators for valves and like devices in which it is required that a minimum of energy be exerted to move the device between two conditions. Although the invention is particularly applicable to the control of water flow in automatic sprinkling systems, it is also applicable to other types of control systems.
2. Description of the Prior Art
In automatic water sprinkling systems, valves may be distributed in different locations in areas to be sprinkled and may be actuated by electromagnetic actuators under control of a timer or timers to open the valves at different selected times.
Water pressures on the order of 80 to 100 pounds per square inch are normally encountered in the operation of such systems. Therefore, sprinkler valves must be of sufficient size and ruggedness to safely and reliably handle such pressures at rates of flow required for sprinkling systems without leakage or malfunction. Heretofore, such valves required electromagnetic actuators of considerable strength or required relatively expensive pilot operated fluid actuators, for proper and reliable actuation, thereby requiring relatively large electric currents for energization or critical pilot valves of small size and force. This, in turn, precluded the use of batteries which might be otherwise located directly adjacent to the valves, but required that the valve actuators be connected to sources of current, such as regular household supply terminals, by wire conductors. Since the water control valves may be widely distributed throughout an area to be sprinkled, such conductors must be strung, either under ground or over the ground, between the various valves and the current supply source.